In principle, various types of storage shelf units are known. The suitable type of storage shelf unit is selected depending on the storage goods to be stored and the space available for accommodating the storage shelf units. A quick access to the storage goods without any great loss of time is supposed to be possible. Particularly in the case of high-rise storage units, the large dimensions of the storage shelf units can result in long travel times for storage and retrieval.
On the one hand, storage shelf units are known that follow the paternoster principle, which is also frequently referred to as the circulation principle. Moreover, storage shelf units are known which comprise two opposite shelving columns and a transport shaft situated between them, with a rack conveyor traveling up and down in the transport shaft and delivering the storage goods to the storage locations or removing them from the storage locations. These storage shelf units are often referred to as storage lift or vertical storage shelf unit.
Depending on the storage space requirements and the number of storage goods to be stored, several of such storage shelf units are set up, standing side-by-side, in order to form a storage system. Generally, every storage shelf unit has a service opening.
A storage system comprising three storage lifts is known from DE 203 05 773 U1, wherein the storage lifts each have a service opening and these service openings surround a work surface on at least three sides. Every storage lift comprises opposing shelving columns, a central transport shaft and a conveying unit that can be moved within this transport shaft.
However, it has proved disadvantageous that a lot of storage space is lost due to the arrangement of one service opening, respectively, in each of the storage lifts. Moreover, a lot of storage capacity is lost also due to a transport shaft with an associated rack conveyor being provided in each of the storage lifts. Furthermore, in the event that three deposited storage goods items are required, of which each storage goods item is located in a different storage shelf unit, the operator has to operate each storage shelf unit and remove the storage goods item individually from each service opening. Thus, the handling of several storage shelf units and an increased amount of time is required.